pbio/sys/battery: Reduce battery-full threshold voltage.

Some batteries stabilize just above 8200 mV. This is as full as they get, so indicate that it is ready with the green light.

This helps people avoid charging their hub longer than needed.

Author: laurensvalk

CHANGELOG.md

@@ -7,6 +7,8 @@
 ### Changed
 - Changed order of the `DriveBase.arc` method. This method has not yet been
   released or documented, so this is not a breaking change ([support#1157]).
+- Reduced voltage threshold at which the charging light goes from red to green
+  to indicate that the battery is full from 8300 to 8190 mV ([pybricks-micropython#292]).
 
 ## [3.6.0b4] - 2025-02-14
 

lib/pbio/sys/battery.c

@@ -20,7 +20,7 @@
 #define BATTERY_CRITICAL_MV     4800    // 0.8V per cell
 
 // These values are for LEGO rechargeable battery packs
-#define LIION_FULL_MV           8300    // 4.15V per cell
+#define LIION_FULL_MV           8190    // 4.095V per cell
 #define LIION_OK_MV             7200    // 3.6V per cell
 #define LIION_LOW_MV            6800    // 3.4V per cell
 #define LIION_CRITICAL_MV       6000    // 3.0V per cell